but first, it is the day for what is being billed as the biggest event in music history. >> and the concert is called 12-12-12. should be national sound check day, but it takes place tonight at new york's madison square garden. on the bill, bruce springsteen, the who, paul mccartney, bon jovi, eric clapton, billy joel, your girl alicia keys is going to be there. chris martin, kanye west, and believe it or not, more. and it all goes to benefit survivors of hurricane sandy. >> cool day, great cause. nicely done. as with all magic numbers, brides and grooms like to get hitched. >> this is an easy way for the husband to remember the anniversary. an arizona couple is giving their whole wedding the theme of 12, inviting 12 guests to be there, tying the knot at 4:12. one of at least five couples getting married at the same place today. david's bridal estimates there are about 7,500 nuptials across the country today.